Fluorescence in diamonds: Are fluorescent diamonds always milky?

Introduction to Diamond Fluorescence

Have you ever heard about diamonds that glow under UV light? This might sound like something out of a sci-fi movie, but it's a real phenomenon known as fluorescence. Whether you're shopping for an engagement ring or just curious about these sparkling stones, understanding diamond fluorescence can help you appreciate their unique beauty. Let's dive into the world of glowing diamonds and see what all the buzz is about.

Here you can see two diamonds with and without UV light. Both look the same under normal light.

What is Diamond Fluorescence?

So, what exactly is diamond fluorescence? Simply put, it is the visible light that some diamonds emit when exposed to ultraviolet (UV) light. Imagine yourself in a nightclub with black lights making your white clothes glow. That's exactly what happens with diamonds. Most of the time, this glow is blue, but it can also be yellow, green, or even white, depending on the diamond's chemical composition.

Causes of Fluorescence in Diamonds

Fluorescence occurs due to trace elements in the atomic structure of the diamond. Elements like nitrogen or boron are often the cause. When these elements absorb energy from UV light, they get excited and release this energy as visible light. It's a bit like the natural glow of fireflies - a fascinating and beautiful process.

Prevalence of Fluorescence in Diamonds

You might wonder how common this phenomenon is. Well, about 25% to 35% of diamonds show some degree of fluorescence. However, only about 10% have fluorescence strong enough to significantly affect their appearance. So, while not every diamond glows under UV light, a significant portion of them do.

Especially with side diamonds (melee), they are not sorted by fluorescence. For example, you can see in this diamond bezel of the watch that some show fluorescence. This did not affect whether the diamonds were beautiful in this watch.

Fluorescence Grading Scale


Source: https://4cs.gia.edu/en-us/blog/fact-checking-diamond-fluorescence-myths-dispelled/

Just like diamonds are graded on cut, color, clarity, and carat, fluorescence has its own grading scale. Here is a quick overview:


No fluorescence detected.


Barely noticeable fluorescence, usually only visible under strong UV light.


Visible under UV light but usually does not affect the diamond's appearance in normal lighting.


Clearly visible under UV light and can slightly affect the diamond's appearance under certain lighting conditions.

Very Strong

Very noticeable, can affect the diamond's appearance even under normal lighting.

Impact of Fluorescence on Diamond Appearance

Let's now talk about how fluorescence can affect the appearance of a diamond. Opinions vary here.

Positive Effects

For diamonds with lower color grades (I-M), fluorescence can actually be a bonus. The blue glow can counteract a yellowish tint and make the diamond appear whiter and more appealing. It's like a little magic trick of nature to enhance the diamond's beauty. These diamonds are especially popular in larger carat weights: you get a diamond that appears whiter at a better price.

Often, special designs can also be implemented that only the wearer of the piece of jewelry knows about or that become visible, for example, in a disco. These designs are also known as "disco diamonds".

Source: https://rapaport.com/magazine-article/designers-creating-magic-with-fluorescent-diamonds/

Negative Effects

It is often said that strong or very strong fluorescence can sometimes cause diamonds to look hazy or milky, especially in higher color grades (D-F).

Over the years, we have examined thousands of diamonds in our in-house lab. We found that fluorescence DOES NOT affect whether diamonds are milky or not.

Milky appearance often has other reasons (mostly in the crystal structure of the diamond). Even a diamond with very strong fluorescence can be completely clear, and a diamond with none can be completely milky.

Fluorescence and Diamond Value

How does fluorescence affect the value of a diamond? This is a question many buyers ask, and the answer can be quite complex.

Colorless Diamonds (D-F)

For colorless diamonds, strong fluorescence can be seen as a negative aspect. These diamonds are often sold at a discount because fluorescence might be perceived as a flaw that could affect their pure, transparent appearance.

However, as mentioned above, it depends more on whether the diamond is milky or not. You can buy very beautiful diamonds with strong fluorescence at a better price. We pay attention to over 30 factors that influence a diamond's beauty and are not influenced by certificates. See also "Why a GIA certificate and Excellent Cut is no guarantee that the diamond will also be beautiful".

Lower Color Grades (I-M)

Conversely, fluorescence can be very desirable for diamonds in the I-M color range. The added whiteness provided by the blue glow can enhance the diamond's overall appearance, sometimes resulting in a price premium.

Expert Opinions and Studies

Experts and studies from institutions like the GIA suggest that fluorescence generally has minimal impact on a diamond's appearance and structural integrity. The key takeaway here is that while fluorescence can affect a diamond's look, this effect is usually subtle and not a dealbreaker for most people.

Should you buy a fluorescent diamond?

So, should you buy a diamond with fluorescence? It really depends on your personal preferences. Some people love the unique glow and the potential enhancement in lower color grades, while others prefer the pure look of a non-fluorescent diamond. The best advice is to view diamonds under various lighting conditions before making a decision. This way, you can see firsthand how fluorescence affects the diamond and decide if it's the right choice for you.

Fluorescence is only an identification criterion and not a bad thing.

Understanding diamond fluorescence adds another layer of appreciation and complexity to choosing the perfect gemstone. This phenomenon, caused by trace elements like nitrogen or boron, can either enhance or diminish the beauty of a diamond depending on its color grade and the intensity of the fluorescence. Whether you find the glowing effect magical or prefer a diamond without it, always view the stones under various lighting conditions to see what appeals to you most. For those in Munich and Augsburg, Designer Diamonds can help you find the correct ring size to ensure a perfect fit for your dazzling diamond.

Diamond fluorescence is listed on diamond certificates to add another identification feature. Simply put, if you have a certificate that states "None" fluorescence but the diamond shows some, identification can be made within seconds using UV light. 


1. What is diamond fluorescence?

Diamond fluorescence is the glow that some diamonds emit under UV light, typically blue, but sometimes other colors.

2. Is fluorescence common in diamonds?

Yes, 25% to 35% of diamonds show some fluorescence, with a smaller percentage showing strong fluorescence.

3. Does fluorescence affect a diamond's appearance?

Usually, it has little to no effect. There is a common belief that strong fluorescence can sometimes cause a hazy appearance or enhance the whiteness of diamonds with lower color grades.

4. How does fluorescence affect the price of a diamond?

Fluorescence can both increase and decrease the price of a diamond, depending on its color grade and the strength of the fluorescence.

5. What causes fluorescence in diamonds?

It is caused by trace elements such as nitrogen or boron in the diamond, which emit visible light when exposed to UV light.

6. Can fluorescence be seen in normal lighting?

Normally, it is only visible under UV light, but some professionals might detect faint fluorescence in strong sunlight or certain artificial light sources.

7. Is fluorescence good or bad for a diamond?

It depends on personal preference and the specific diamond. It can enhance lower-color diamonds but might negatively affect colorless diamonds.

8. Does fluorescence affect a diamond’s structural integrity?

No, fluorescence does not impact the diamond’s strength or durability.

9. Why do some jewelers say fluorescent diamonds are hazy?

Haze in fluorescent diamonds is rare and often confused with other internal characteristics like graining. Over the years, we have examined thousands of diamonds and found no connection between milkiness and fluorescence.

10. Should I buy a diamond with fluorescence?

It's a personal choice. View the diamond under different lighting conditions to see if you like the effect. Avoid strong fluorescence in colorless diamonds but consider it for lower color grades. Sometimes, unique designs can be implemented as a hidden bonus, also known as "Disco Diamonds".

11. Do Lab Grown Diamnods also have fluoresence

Yes, Lab Grown Diamonds also have fluoresnce. Somtimes the type and color is used for identification

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